JPS63500020A - Method for removing SO↓2, NOx and particulates from mixed gas using streamer corona - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Remove S02, NOX and particulates from mixed gas using streamer corona Method The present invention is a method for removing sulfur dioxide, nitrogen oxides, and particulates from a mixed gas. It is about law. This invention is based on the United States Doe Contract (If, S, DOE Contract) No. DI! -AC-22-83PC60,266 Originally completed. Therefore, the United States federal government has certain rights to this invention. have an advantage.

Emissions of exhaust gas containing dioxide ions and/or nitrogen oxides and/or particulates There are many sources. For example, coal-fired power plants, iron and steel plants, and paper mills. , acid production plants including sulfuric acid and nitric acid, and internal combustion engines. Ru. The above pollutants can cause photochemical smog and acid rain. Also , inhaling these pollutants is harmful to the human body. So, something like this Many methods are being considered to remove pollutants from exhaust gases before they are released into the atmosphere. . For example, many coal-fired power plants use wet or dry methods for S02 removal. gas cleaning equipment is used, and cyclones and electrostatic sedimentation equipment are used to remove particulates. A bag filter is used. However, this method requires a large investment is required, and the operating costs are high. In particular, nitrogen oxides (hereinafter abbreviated as NOx) difficult to remove. For this reason, the operating parameters of the flue gas emission equipment should be adjusted. In many cases, the amount of NoX generated is simply minimized. by the plant The generation of S02 can be reduced by burning coal with low sulfur content. are doing. However, in this case, fly ash fine particles with high resistivity are formed. However, it is difficult to collect these fly ash fine particles using an electrostatic sedimentation device. Recently, Excite the exhaust gas like a radical by irradiating it with a high-energy electron beam (~IMeV) removes SO□ and NOx by generating chemically active species in the activated state. A method was developed to Radicals convert NO2 and NOx into fine particles or mist. Since it has the function of promoting the reaction of S It becomes possible to recover O□ and NO8. Regarding this method, for example, See US Pat. No. 4.004.995 and US Pat. No. 4.435.260. sea bream. This method requires a large number of electron beam accelerators and is therefore very expensive. Karu.

Also, this method only induces radiochemical-type chemical reactions [B, D]. B., D. Blaustein, “Chemical Reactions Under Discharge ( Chemical Reactions in Electrical Disc harges) J (Paper) No. 11, Advances in Chemistry Series (Ad-van ces in Chemistry 5eries) (80), Nice Niss , Washington, D.C. (ACS, Washington, D.C.) ), edited by RlF, Gould (1969)].

A method that promotes chemical reactions by generating chemically active species in an excited state in a gas. There are several types of laws. However, most methods use ionizing radiation or electrical discharges. It is. The ionizing radiation method uses α-rays, β-rays, γ-rays, ultraviolet rays, X-rays, and high-energy An electron beam or the like is used. In the case of chemical methods using electrical discharge, lower gas pressure is used. Alternatively, several methods are used to raise the discharge temperature (Plaustein, "Discharge"). Chapter “Chemical Reactions Under Electromagnetic Conditions” (Paper No. 36), edited by Earl, F. and Gould (196 9 years)].

For low-pressure discharge, electromagnetic fields such as radio frequency waves or microwaves are used. Includes electrical discharges, laser-induced discharges, and direct or alternating current glow discharges. [Chapter 22.24.29.35 of Plaustein's "Chemical Reactions Under Discharge" (paper number), Chapter 2127 (paper number), Chapter 3.12 (paper number) and E., L., Steinfeld (J., L., 5steinfeld), eds. Laser-Induced Chemical Proc -esses) J (1981), Plenum Press (Plenum Pre ss) Inc., New York]. For discharges at high or atmospheric pressure, e.g. These include alternating current corona, arc discharge, silent discharge, and streamer corona.

High-pressure discharges are very suitable for promoting chemical reactions at atmospheric pressure. normal roller A discharge is a process in which a large DC or AC voltage is applied to an asymmetric electrode in a gas close to atmospheric pressure. It is generated by applying an electric current. For example, a plate-shaped A large negative DC voltage is applied to a point electrode placed near the electrode. Then high voltage Therefore, an electric field is generated between the electrodes. This electric field is non-uniform, and the vicinity of the point electrode is It has the strongest electric field. For this reason, gas insulation is not maintained near the point electrode. Then a corona discharge occurs [L, Loeb]'! Qi Corona The physical basis of the EI electrical Coronas: Thei r Ba5ic Physical Mechanism) J California University Press (Univ, of Calif, Press) (1965) , and “Electric Breakdown of Gases” (eds. Meek et al.) al Breakdownof Ga5es) J (1978), John Wiley & Sons (John Wiley & 5ons). Io A current consisting of electrons and electrons flows across the gap between the electrodes. near the point electrode Energy is given to electrons by a strong electric field. Electrons collide elastically with gas molecules, but Because the difference in mass between electrons and ions is extremely large, electrons do not lose energy when they move.

Electrons with sufficiently large energy collide inelastically, and the electrons release energy into gas molecules. Energy moves. As a result, the gas molecules become excited. Gas molecules and electrons Because the energy obtained from the collision is released as light, the glow characteristic of corona discharge occurs. Occur. Excited gas molecules also participate in chemical reactions. In other words, gas molecules dissociate (resulting in the formation of radicals that accelerate chemical reactions).

The most energetic electrons ionize gas molecules, creating more free electrons. generate. These free electrons obtain energy from the electric field and further ionize gas molecules. to become This phenomenon is generally called an electron avalanche, and when this phenomenon occurs, The current increases exponentially. The electrons (as they move through the interelectrode gap) It moves away from the electric field region and now enters the low electric field region. In this low electric field region, electrons We don't get much energy from electric fields. These low-energy electrons attach to gas molecules. They form negative ions, which move toward the grounded electrode. Io obtains energy from an electric field. However, unlike electrons, ions interact with gas molecules. Energy is lost due to elastic collisions. Ions and gas molecules have almost the same mass, so luck Dynamic energy is transferred from the ions to the gas molecules. As a result of this, the temperature of the gas increases. rise Even when ions collide with gas molecules, the gas molecules do not become excited. follow Therefore, this collision cannot promote chemical reactions. In other words, the ionic current does not contribute to the progress of the chemical reaction and is wasted simply to heat the gas. . Near the point electrode, the current flowing between the electrodes contains only electrons, so this point Excited gas molecules and radicals are generated only in a small area around the electrode. electric Most of the current flowing between the electrodes is ionic current. Therefore, excited gas molecules (active species ) and radicals. Active species are only a small part of the electrode. Since it is generated only in the area, the generation rate is low and the volumetric efficiency is also poor.

Recently, experiments have been conducted to remove NOx from gas streams by generating DC and AC corona discharges. Conducted in Japan [Tamaki et al., Journal of the Chemical Society of Japan (The Chemical 5oci ety of Japan) Volume 11, page 1582 <1979)]. deer However, the energy efficiency and removal rate were found to be low. Excluding SO2 and NOX A method using corona discharge to eliminate Electrical comprehensive control method for pollution caused by Inter-grated Po1lution Control for C ombustion Ga5es)J Doctoral thesis, Department of Electrical Engineering, Faculty of Engineering, University of Tokyo (198 4th year)].

Arc discharge can also be used to accelerate chemical reactions [Plaustein “Chemical Reactions Under Electric Discharge” Chapter 33 (paper number), American Chemical Society Press ( American Chemical Society Publication s)) o However, arc discharge is very different from corona discharge. Ah A filament is a thin filament that connects two low voltage electrodes; A high current flows through the filament. (On the contrary, corona discharge is a low-current, high-voltage pressure). This arc filament is heated to extremely high temperatures by passing a high current through it. heating (e.g. arc welding). Arc discharge uses high current, Energy is used to heat the gas, so it takes energy to cause a chemical reaction to occur. The energy efficiency is very poor. In addition, only one arc filament is used, so However, since its volume is small, the volume that can be processed is small.

Silent corona discharge (silent corona discharge) consists of a dielectric layer (e.g. glass) and a small Parallel or concentric to each other separated by an air gap (~1 mm>) It can be generated by applying an AC high voltage between the electrodes. Electricity generated The field is uniform across the air gap. This is normal DC or AC corona In contrast, a non-uniform electric field is used to generate the . There is a dielectric layer Because of this, sparks can be prevented. Therefore, the air is distributed evenly between the air gaps. It becomes possible to generate electricity. Silent corona discharge accelerates chemical reactions in the gas phase [Plaustein, "Chemical Reactions Under Electric Discharge"] No. 17.25.26.28 (paper number) American Chemical Society Press.”

Ozone generation is one of the oldest applications of silent corona discharge. [Rice et al., “Ozone Technology and Applications (Ozone Tec hnology and Application) J pages 1-84 (1 982), and U.S. Patent No. 387.286 (1888), No. 587.770 (1897)]. Silent corona discharge of dry air When passing through a liquid, the 02 molecules dissociate to some extent and become 02-. 02 Ichihara Many of the children combine with 02 molecules to form ozone (03). improved sire The corona discharge method is one of the best ozone production methods currently available. It has become one. According to this improved silent corona discharge method, the silent corona To generate a discharge, an alternating current or high frequency alternating current (high voltage of 1 to 10 kt(z) is required). is used. However, the ionic current generated by the discharge is used to heat the gas. Therefore, energy efficiency is poor. Generally, the wasteful heat generated can be removed by cooling the electrode with liquid. [U.S. Pat. No. 3,766,051 (1973]) ]. In this method, the waveform of the applied high voltage is appropriately shaped to create a silent control. Improve energy efficiency by reducing ion current caused by Rona discharge. It is possible to [U.S. Pat. No. 4.016.060 (1977 Year)〕.

Even if a high DC voltage is applied between two electrode plates in the atmosphere, there is almost no electric current between the two electrode plates. The current doesn't flow. As the voltage is increased, a spark suddenly occurs between the two electrode plates (insulation breakdown). damage), effectively causing a "short circuit" between the two electrode plates. Then, a large current flows and the power supply circuit The breaker shuts off. Research using high-speed photographic technology has revealed that stress can be detected just before dielectric breakdown. It was found that the reamer propagated between the two electrode plates [L, B, Loeb, "Electric Corrosion"] "Physical basis of the mechanism of development", pages 143 and 167 (1965) Caliph Fornia University Press and Meek et al., “Electrical Breakdown of Gases”, page 439. John Wiley & Sons, Inc. (1978).

The streamer causes spark-type breakdown, so this streamer has a long lifespan. Life is very short.

Applying a high voltage pulse (200 nanoseconds) between asymmetric electrodes for an extremely short period of time A stable streamer discharge can be formed by this. High voltage is applied During this 200 nanosecond period, the streamer propagates between the electrodes. (between pulses) The high voltage is turned off and the streamer is extinguished, preventing insulation damage due to sparks. There is not enough time for destruction to occur.

When a large number of high voltage pulses are applied per second, the IJ-macorona discharge occurs. occurs (brush-like discharge consisting of numerous filamentous streamers). This su) IJ-Makoro Na discharge can be used to accelerate chemical reactions. This stream makoro Most of the current during a discharge is due to electrons. This is because electrons are more powerful. This is because it is 500 times easier to move than when it is on. Can accelerate chemical reactions Since it uses electrons rather than ions, it is energy efficient. The streamer is between the electrodes Since it passes through the entire gap, the rate at which active species are generated increases. stream mako Rona discharge differs from normal corona discharge or silent corona discharge in the following points: There is.

(1) The active species generation region is a small glow region near the point electrode or uniform near the dielectric layer. A brush-like streamer that propagates across the gap between electrodes rather than in the glow region This is an area made up of. Therefore, the active high electric field at the streamer tip The area also propagates across the interelectrode gap.

(2) Electrons make a large contribution to the current of streamer corona discharge.

On the other hand, the current of corona discharge and silent corona discharge is mostly ion electric current. It is a flow.

(3) Streamers are generated by very short (200 ns) high voltage pulses.

On the other hand, corona discharge and silent corona discharge are generally or caused by periodically changing high voltages.

Normal corona discharge and silent corona discharge are generated by pulses (usually pulses longer than 1 microsecond are used). However, the streamer corona release corona discharge and silent corona discharge, as the actual physical mechanism is different from that of It is necessary to distinguish between this and streamer corona discharge.

Ordinary corona discharge is mainly used to carry out electrostatic sedimentation methods [H. White (H, White) [Industrial electrostatic precipitation method (Industrial) Electrostatic Precipitation), 1 Addison Addison-Wesley, Bergamon Press (Pe rgamon Press), Oxford, 1963, and Varnish, Oglesby (S, 0g1esby) et al. ``Electrostatic sedimentation method (Electro- static Precipitation) J Pollution Engineering and Technology Series Pollution Engineering and Technology y 5eries), Young (other lines), Marcel Roudecker (Ma Rcel-Dekker), New York (1978)]. Generally, electrostatic In the sedimentation device (hereinafter abbreviated as ESP), the negative electrode is connected to the electrode in the form of a wire plate. A direct current corona discharge is generated to remove particulate matter from the gas stream. This fine grain The child substances are charged and attracted to the plate-like electrodes, forming a layer. lighten this layer If you shake it (vibrate it), it will fall into the hopper. To make the polarity negative, change the polarity This is because the recovery rate of fine particles is better than that of positive setting.

Pulsed corona discharges of negative polarity are also used in electrostatic sedimentation devices. Ichi, White's above-mentioned document, as well as U.S. Patent No. 2.000.017. No. 2.509.548]. When using pulsed corona discharge, high voltage is applied. It doesn't spark even though. This results in a pulsed motion along the surface of the wire. However, a uniform corona discharge occurs and the ionic current density in the gap between the electrodes decreases. [H, Milde] Information on electrical insulation Newsletter (IEEE Transaction on Electrical In5 ulation) Volume El-17, No. 2, Page 179, April 1982] Because the ion current density is reduced, the fine particle layer that normally forms on the collection electrode is By reducing the voltage difference on both sides, undesirable back corona occurs. can be prevented. The back corona is caused by the voltage difference on both sides of this fine particle layer. This occurs when the breakdown voltage of the fine particle layer becomes larger than the breakdown voltage of the fine particle layer. Oppositely charged ions are released into the gas stream.

Pulsed corona discharge differs from streamer corona discharge. S) IJ-Ma A corona discharge consists of numerous filamentous streamers extending across the gap between the electrodes. In contrast, pulsed corona discharge is a uniform glow near one electrode.

Streamer corona discharge (of negative polarity) is carried out in a Boxer-type charging device. Plasma is generated between spiral electrodes placed close to each other (20 mm). It is used for. Negative ions are extracted from the electrodes by high alternating voltage.

These extracted ions charge the particles in advance before entering the ESP. Used for [varnish, Masuda, knee, Mizuno], Conf, Rec, of IEEE/IAs Annual Meeting, Philadelphia, Pennsylvania, 1066 pages (1981)]. Masuda et al. used a streamer corona discharge of negative polarity to Succeeded in generating plasma in the immediate vicinity surrounding the wire electrode in the SP are doing. In addition, by using a negative polarity DC high voltage, it is possible to remove the plasma from the plasma region. A highly uniform negative ion current is drawn towards the gap between the electrodes et al., Conf, Rec, of IEIEIE/IAS Annual Meeting, Mexico City, 9 66 pages (October 1983)].

Additionally, a streamer corona discharge is generated in a transportation line type ozone generator to dry the product. 0. Recently, it has become common to generate . [varnish, ma Sudha et al., Conf, Rec.

of IEEE/IAs Annual Meeting, Chicago, Illinois, 978 pages (1984) 802 is also removed from the airstream by I, Nis, Talements (J, S, Clements), R, H, De Avis (R, H, mouth avis) Conf, Rec, of IEEE/[AS General Conference Chicago, Illinois, 1015 Hage (October 1984)]. This system The system uses electrodes consisting of a point electrode and a plane electrode to Streamer corona discharge was promoted inside. 60 per second for point electrodes Apply high voltage pulses (peak voltage 45 kV, pulse width 200 nanoseconds) at a frequency of did. Air containing 21,500 pp of SSO and water vapor is generated by streamer corona discharge. A significant amount of SO2 was removed from the air stream. Removal of S02 using this system The removal method uses a high-energy electron beam or ordinary DC corona discharge to remove SO2. compared with the law. In this method using streamer corona discharge, the supplied energy The energy efficiency was better than other methods. In addition, this Strifko With the Rona discharge method, additives (such as NH, etc.) that are required when using other methods It was possible to obtain powder without any powder.

At present, chemical reactions using streamer corona discharge are When generating ozone with a gas generator, and using a configuration consisting of a point or rod electrode and a flat electrode. It is only used to remove sulfur dioxide from humid air using electrodes.

The object of the invention is to prepare sulfur dioxide and/or nitrogen oxides in mixtures with other gases. To improve the conventional method using streamer corona discharge, That is.

Another object of the invention is to remove sulfur dioxide and/or nitrogen oxides and/or Streamer corona emitters that can remove particulate matter from mixtures with other gases. The purpose is to provide a method using electricity.

The present invention embodies four separate discoveries:

First, the present invention eliminates sulfur dioxide within the region where streamer corona discharge is occurring. and/or the method of removing nitrogen oxides is defined by a special arrangement of electrodes. This can be greatly improved by bringing the mixed gas into contact with the streamer corona discharge within the region. It is based on the discovery that there is noh.

Second, the present invention provides (1) a stream within a region defined by a special arrangement of electrodes; Sulfur dioxide and/or nitrogen oxides are removed by generating macorona discharge. (2) At this time, there is no particulate matter in the mixed gas. If present, removes sulfur dioxide and/or nitrogen oxides from this gas mixture. This is based on the discovery that there is an additional effect that changes the rate of completion.

Thirdly, the present invention uses a voltage in which a high voltage pulse is added to a high voltage DC bias. The generated streamer corona may collect particles with high resistivity from the gas flow. based on the discovery that it is effective to reduce and/or eliminate

Fourth, the present invention simultaneously removes S02, NOx, and particulates from the gas stream. However, the stress generated using a voltage that is a combination of high voltage DC bias and high voltage pulses is It is based on the discovery that reamer coronas are effective.

According to one embodiment of the invention, sulfur dioxide and/or nitrogen oxides are to convert it into a separable form in a gas mixture with at least one other gas. within the streamer corona discharge region defined by closely spaced electrodes. The above mixed gas is passed through and a sufficiently large pattern is created within this streamer corona discharge region. Pulsed streamer by periodically dissipating the electrical energy of the pulse voltage Acidifying sulfur dioxide and/or nitrogen oxides by continuously generating corona discharge into fog and/or aerosol particles, The above streamer corona discharge can be carried out using wire cylinder type electrode arrangement or wire plate arrangement. It is characterized by an improvement in that it is generated in the area between the electrodes of a flat-type electrode arrangement. An improved method is provided.

A bias voltage may also be applied to the streamer corona discharge region. Then, the strike Ions produced during reamer propagation are collected between the two pulses.

If necessary, from the gas mixture using any suitable conventionally known method. Aerosols may be removed.

According to another embodiment of the invention, sulfur dioxide and/or nitrogen oxides and /or particulate matter can be separated in a gas mixture with at least one gas A method of converting into a form, The above-mentioned mixed gas and/or the above-mentioned particulate matter are placed in a wire cylinder type electrode arrangement. or electrodes for discharge of electrodes spaced apart from each other, including wire plate electrode arrangements. and the streamer corona discharge region defined by the collection electrode, (1) Electrical energy of sufficient pulse voltage is applied within this streamer corona discharge region. By dissipating it periodically, pulsed IJ-McCorona discharge can be generated continuously. (2) applying a bias high voltage to this streamer corona discharge region; sulfur dioxide and/or nitrogen oxides in an acidic mist and/or aerosol. converting it into particles and charging the aerosol particles and/or the particulate matter. A method characterized in that the method is characterized in that the recovery electrode is directed toward the recovery electrode, and the recovery electrode is used to recover is provided.

Preferred embodiments of the invention will be described below with reference to the drawings.

FIG. 1 shows a wire cylinder type electrode suitable for carrying out the method of the invention. FIG. 2 is a cross-sectional view of the device.

FIG. 2 is a layout diagram of a wire plate type electrode suitable for carrying out the method of the present invention. It is.

Figure 3 shows the wire cylinder type strut used to measure the effectiveness of the method of the invention. FIG. 2 is a cross-sectional view of a reamer corona reactor.

Figure 4 is a block diagram of the power supply for generating streamer corona discharge. It is mu.

Figure 5 shows the ideal applied voltage waveform for generating streamer corona discharge. FIG.

FIG. 6 shows the removal rate of sulfur dioxide using the method of the present invention.

Figure 7 shows streamer corona discharge and direct current when using a wire cylinder type electrode. It is a graph showing voltage-current characteristics of corona discharge.

Figure 8 shows the suspended fly ash removed from the gas mixture according to the method of the present invention. A graph showing the distribution of electric charge with respect to the radius of fine particles and A graph showing the distribution of the charge amount with respect to the radius of the suspended fly ash fine particles removed from the mixed gas. It's rough.

The present invention uses a streamer corona to extract SO2 and/or NoX from a gas stream. and/or a method for removing particulate matter.

One of the features of the present invention is that it is an improvement over the aforementioned SO□ removal method of Mizuno et al.

This feature of the invention is similar to the point (or rod) electrode and planar electrode in the discharge area of Mizuno et al. Wire cylinder type electrodes or wire plate type electrodes instead of electrodes consisting of Using this method, Mizuno et al.'s method is dramatically better than expected. Based on discovery.

Furthermore, the present invention provides for Particulate matter can be removed using wire cylinder or wire plate electrodes. Sulfur dioxide and/or nitrogen is extracted from this gas mixture in the trimmer corona discharge area. It is based on the discovery that it is effective in removing oxides.

Another feature of the invention is that under a special electrode configuration sulfur dioxide and/or nitrogen oxides and/or particulates by This is a new method for removing gaseous substances from mixtures with other gases.

Yet another feature of the invention utilizes streamer corona discharge with a special electrode configuration. This is a new method of coagulating particulate matter suspended in a gas stream using This is the point.

In carrying out the present invention, the gas flow is connected to a wire cylinder type electrode (FIG. 1). in the streamer corona discharge region between the electrodes or wire plate type (Fig. 2) The streamer between the poles is passed through the corona discharge region. Streamer Corona is Connect the cylinder or plate electrode to ground and apply power to the wire electrode. It is generated by applying a voltage. As shown in Figure 5, the power supply Use a device that can repeatedly generate high-voltage pulses with a fast rate and narrow width. Ru. It is desirable that a DC bias voltage be applied to this pulse. Cylinder Apply this voltage to the electrode or plate electrode and connect the 1-wire electrode to ground. It is also possible to

However, it is usually inconvenient to do so. The wire electrode is made of a known insulator, e.g. For example, ceramic is used to electrically insulate the cylinder electrode or plate electrode.

To prevent current from flowing and sparks along the surface of the insulator Normally, the length of the path connecting both electrodes along the surface of this insulator is the maximum. In addition, the surface of this insulator must be kept clean. spa The DC voltage has a greater influence on the arc than the pulse width, so what should we do? However, if necessary, lower the DC bias voltage to avoid sparks on the insulator surface. It is also possible to reduce the possibility of this occurring.

A voltage waveform such as that shown in FIG. 5 can be generated in a variety of ways. child One of the preferred methods for A high-voltage DC power supply is connected in parallel to the ear electrode, and a high-voltage pulse power supply is connected in series. There is a method of connecting a high-voltage capacitor. High voltage capacitors withstand narrow pulses Allows voltage to pass and blocks DC voltage.

As a result, no DC voltage reaches the high voltage pulse power supply. Therefore, the DC A high voltage pulse is superimposed on the ias voltage. High voltage pulses are It can be generated using various well-known high-voltage power sources using an electric power source. High speed speed As a switching device, a high Speed mechanical switches, triggered spark gaps, thyradons, silicon controlled rectifiers, etc. Can be mentioned. Largest switching speed (faster rise, narrower pulse width) ) Use a spark gap. To maximize energy efficiency in the removal process can optimize pulse shape, rise time, height, width, and repetition rate. The most energy efficient pulse power source should be used. The entire removal process If the efficiency (cost and operational efficiency) of It is also possible to shift the meter from its optimum value and use a more efficient power supply.

There are two removal methods. In the first method (conversion), the gas S02 and/or converts NOx into a mist or particulate form. But this converted No gas is recovered. In the second method (conversion and recovery), the gaseous 802 and and/or converts NOx into fog or particulate form and eliminates any other particulates present. Collected together with child substances. Which method to use depends on the level of the DC bias voltage. can be determined by controlling the In other words, when only converting When the DC bias voltage is set to zero or a small value and both conversion and recovery are performed, Increase the DC bias voltage. When performing only conversion, use an AC bus with changing polarity. Easing voltage can also be used.

In both cases, the streamer corona is generated by high pressure pulses. Each pulse While it is turned on, a thread-like thread radiates outward from the wire electrode. J-ma propagates. Streamer corona occurs along the wire electrode; The length of the ear electrodes is determined by the amount of energy each high voltage pulse has. Therefore, Multiple power sources and multiple sets of electrodes may be required when processing large amounts of gas. There is sex. For best performance, pulse rise times should be as short as possible. The peak voltage of the pulse can be maintained within a range that does not generate back corona or sparks. It has to be made bigger. If the pulse width is too wide, the streamer will go to ground. This streamer forms a conductive bridge between the electrodes as it makes contact with the connected electrodes. do.

This causes a large ionic current to flow, creating a spark.

Therefore, to generate a stable streamer corona, high DC or AC voltage is not necessary. Appropriate. Optimal value for pulse width (this value depends on pulse voltage, gas temperature and pressure, electrode (depending on the configuration of the streamer) is long enough to allow streamers to spawn and propagate. Moreover, while this pulse is on, sparks are generated and large ions are generated. This is a sufficiently short value so that no current flows. After applying the pulse The delay time until the J-ma is formed becomes shorter as the applied voltage is increased. child The delay time is approximately 1-100 nanoseconds. Streamer transmission in air at room temperature and pressure Typical values for transport speed are approximately 10" cm/sec.

Therefore, under these conditions, the time required for the streamer to propagate 5 cm is approximately 50 nanoseconds. (plus delay time). [R, 17. 7 Fu 77, Ra ( R, F, Fernsler) Fluid Physics (Phys.

Fluids) J Volume 27, No. 4, Page 1005 (1984).

Formation of chemically active species by streamers is primarily due to inelastic scattering. It is. In other words, high-energy electrons are activated to bring gas molecules into an excited state. Seeds are formed.

) While the IJ-mer is propagating, an electric current is generated in the high electric field region near the tip of this streamer. Many child avalanches occur. Electrons within this region gain sufficient energy from the electric field. and excite gas molecules. The number of gas molecules that become excited increases as the electric field becomes stronger. There will be many. Streamers are particularly suitable for generating extremely strong electric fields. and This is because the path of the conductive thread-like streamer has a strong electric field at its tip. , because the space charge of the electric field near this tip increases [Fernsler's Reference above]. Using pulsed high voltage makes it possible to apply higher voltages. Ru. Therefore, the electric field is larger (without sparks) than when using DC high voltage. can be reduced.

To generate a streamer corona, an energy-efficient positive or negative High voltage pulses of either polarity can also be used. However, a pulse with positive polarity Using a pulse of negative polarity produces a longer streamer than using a pulse of negative polarity. . Therefore, if the pulse is positive, the gap between the electrodes can be used more, so the volume Increased efficiency.

S) Improving energy efficiency when only converting gas using IJ-McCorona In order to do this, it is necessary to prevent ions from moving. Because the ionic current is This is because it does not contribute to the generation of chemically active species in an excited state. Io Considering that the mobility of electrons is 11500 times that of electrons, this requires It is particularly preferred to use very narrow pulses with short rise times. of pulse If the width is narrow, most of the current during this pulse on is due to electrons. Ru. Ions, which are slower than electrons, are left in the path of the streamer. The remaining ions It is collected by a bias voltage between pulses. Therefore, the next pulse is Ions left behind during the application do not contribute to the ion current. This operation To achieve the best results, adjust the bias voltage and pulse repetition rate to Preferably, the ions are moved towards the electrode before the pulse is generated. ion The maximum time it takes for , v=bE, E=V/d (where t is time, d is the distance of the gap between the electrodes, ■ is the average velocity of the ions, b is the mobility of the ions, E is the average value of the electric field, and ■ is the bias voltage. It can be estimated using

The average mobility of ions depends on gas composition, pressure, and temperature. This value is normal temperature. For air at pressure it is about 2 cnf/volt-second [Niss, Oglesby, supra. Literature, pages 24 and 35]. Keep the pulse repetition frequency (f) sufficiently low. , ensuring sufficient time for the ions to migrate between the two pulses.

In other words, if the pulse width is narrow, the time corresponding to this pulse width can generally be ignored. Then, set f<l/t. For example, when V=5kV and d=5 is E=1 kV/cm, V=2x 103cm5t=2.5 ms, f <400Hz. Adjust the width of the DC bias voltage required to collect the ions. If the value is greater than the minimum value, the energy will cause the ions to move faster than necessary. It is a waste because it is used for However, when the DC bias voltage is increased, the ion collection time is delayed. This makes it possible to increase the pulse repetition frequency. This increases the processing speed. The pulses are superimposed on the DC bias voltage. Therefore, increasing the DC bias voltage also increases the effective pulse voltage. Therefore , when only gas conversion is performed, the optimum value of the DC bias voltage is may be greater than the minimum required for yield. narrow pulse voltage If necessary, apply a bias voltage whose polarity is reversed synchronously each time it is applied. By doing so, the amount of particles collected using bias voltage can be minimized. . In this case, the ions can be collected in the same way as described above, but (by changing the bias voltage less fine particles are recovered (using the same method). This is because charged particles generally have low mobility. This is because it is less than about 1/400 compared to on [Oglesby's above Literature, page 35].

In the case of gas conversion and recovery methods, the particulate matter is substantially removed between the two pulses. The value of the DC bias voltage must be large enough so that it can be charged and recovered. . There are two main mechanisms by which fine particles become charged, including contact between ions and fine particles. well known. In other words, the charging mechanism is based on an electric field and the charging mechanism is based on diffusion. [Niss, Oglesby and Gee, Nicholas (G, N1cloas) r electrostatic type Sedimentation Method, Chapter 4, Marcel Detzker, New York]. Next, the charged particles , to an electrode connected to ground due to the electric field generated by the DC bias voltage. I'm drawn to it. Most of the highly mobile electrons are exposed to narrow high-voltage pulses. Use a wire electrode with positive polarity, as many positive ions are removed during the process. , positive ions, and positively charged particles are moved toward an electrode connected to ground. can be set. The area where fine particles are charged and collected becomes wider as the electric field is strengthened. Therefore, it is best to apply a large DC bias voltage to charge and collect fine particles. Effective.

However, the DC bias voltage should be lower than the voltage at which DC corona begins to occur, and the It is necessary to prevent continuous DC corona from occurring. Presence of fine particles with high resistivity If a layer is formed on the recovery electrode, the direct current corona will cause There is a risk of coronavirus outbreak. Back corona is the accumulation of charge on this layer. This is caused by. This back corona causes dielectric breakdown in this layer, causing fine particles to form. The particles become suspended again in the gas stream along with ions of opposite polarity. Ba When a corona occurs, oppositely charged ions discharge suspended particles. This conclusion As a result, collection of these suspended particles is hindered, resulting in a significant drop in the collection rate of particles. [Niss, Oglesby and Gee, Nichols, cited above, Chapter 7]. positive dc When a positive streamer corona is generated using a high bias voltage, the DC corona field The back corona is much smaller than in the case of Long positive s)+J-ma is the fine particle layer is actually discharged, and charge is accumulated in this fine particle layer, causing back corona. prevent. However, the peak value, pulse width, and repetition frequency of the pulse voltage are too large. (depending on the resistivity of the fly ash), back corona or sparks are generated. There is a risk that it may occur. For normal processing, the conventional collection electrode is The microparticles collected using the “Taku” method (vibrating by mechanical shock) are drop it into the container. Part of the particles from the particle layer returns to the gas flow (S) If the IJ-ma impacts this layer, then the IJ-ma By shortening the length of the ESP or by using a downstream conventional ESP or baghouse, It is desirable to collect the collected fine particles. Streamer corona generator is ESP The first part of the was changed to a streamer corona generator with a wire plate type electrode. By doing so, it is possible to easily change to the conventional ESP.

It is also possible to remove particulate matter by forming agglomerated particulates. child In the case of The particulates are removed using an ESP or bag filter as before. Collect downstream. Particulate matter returned to the gas stream is formed on the collection electrode. It has a large diameter because it consists of agglomerated fine particles within the layer. Large particle size particles are small particle size particles. This streamer corona is known to be much easier to retrieve than the child. Improves particle recovery when using conventional equipment using agglomerate formation method can be done.

Reference is now made to FIG. The streamer corona generator 10 is a discharge wire electrode. 12 and a recovery electrode 14. A high voltage (positive DC pulse) is applied to the wire electrode 12. voltage) is applied. The recovery electrode 14 is connected to ground. wire A spherical weight 16 is attached to the tip of the electrode 12. This weight 16 is , the function of keeping the wire electrode 12 straight, and the function of keeping the wire electrode 12 straight. The value of the electric field is reduced to approximately the value of the electric field at other positions along this wire electrode 12. There is a function to make them the same. The discharge wire electrode 12 uses an insulator 18. By doing so, it is electrically insulated from the recovery electrode 14 connected to the ground. . Both electrodes are arranged in a conventional wire cylinder type arrangement to form a streak corona discharge region. 20 is formed.

A gas mixture containing the components to be separated enters the device through inlet 22. this After passing through the streamer corona discharge region 20, the mixed gas exits through the outlet 24. child The components contained in the gas mixture may be in the form of fog or particulates and/or in the form of particulates. and collected on the recovery electrode 14. Vibrate this recovery electrode 14 This allows the adhered substances to fall into the hopper 26. non-conducting The surface of the insulator 18 is covered with fog or fine particles using the electric deflection plate 28 and the removal air nozzle 29. Avoid contamination by particles.

FIG. 2 shows a wire plate type electrode arrangement.

A wire electrode 1 is installed between plate electrodes 2.

Example 1 Streamer corona discharge pulses are generated in a wire cylinder type device and can be applied at various temperatures. SO2 from humid air streams containing fly ash and humid air streams containing no fly ash at Removed. The streamer corona generating device 30 shown in FIG. 3 has a wire electrode for discharge. 32 (diameter 3 mm>, probe electrode 34 (length 2.5 cm) and protective electrode It is equipped with a recovery cylinder electrode consisting of 36.38.

A high voltage (positive pulsed DC voltage) is applied to the wire electrode 32 . The above electrode is All made of stainless steel to prevent corrosion. The arrangement of these electrodes has been known for a long time. A streamer corona discharge region 40 is formed in a wire cylinder shape. so that The discharge wire electrode 32 is housed in an insulating member 42, 44 made of Teflon. It has been paid. A length of 5 to 1 Streamer corona discharge region 4 with wire electrode 32 exposed across the 0 mark 0 is formed.

This exposed portion of the wire electrode 32 is covered with a braided cable (not shown). to make the surface rougher. In this way, fine particles adhere to the wire surface. It is possible to achieve the same condition as a dirty wire. Cylinder The entire electrode is housed in a case 46 made of PVC (polyvinyl chloride). This sirin The upper and lower ends of the da electrode are covered using plates 48 and 50 with holes, respectively. ) Ensure that the gas flow passing through the IJ-Macrona discharge region 40 is uniform.

In FIG. 3, the case is housed within a heat insulating jacket 52. Components to be separated A mixed gas containing . This gas mixture is After passing through the macorona discharge area 40, it is discharged from the outlet 56.

S O2 (1000ppm> and water vapor (2.5% by volume, ie 100%RH) was introduced into the apparatus at a temperature of 22-110°C. emitted from this device. The concentration of SO7 in the gas was measured using a dilution system and a pulsed S02 fluorescence analyzer. It was measured using Fly ash with an average diameter of 5 to 10 μm was added to the gas stream using a fluidized bed. We also conducted experiments.

In order to generate a streamer corona, connect the discharge wire electrode 32 to the ground. A voltage having the waveform shown in Fig. 5 is applied between the connected cylindrical protective electrodes 36 and 38. did. The probe electrode 34 for current measurement located in the center of the cylinder electrode is connected to ground via a current measurement circuit with a capacitor for pulse smoothing. ing. The pulse voltage circulates with the capacitor bank as shown in Figure 4. Generated using spark gas [Masuda et al., Conf, Rec, of IE EE/IAS Annual Meeting, Mexico City, United Mexican States, October 1983, 966 pages. ]. This pulse voltage is connected to a DC bias voltage using a coupling capacitor. Overlap. The pulse voltage used in this example had a peak value of +40 to 45k. V, the width was 200 nanoseconds, and the repetition frequency was 60)1z.

The SO2 removal rate when using the above streamer corona generator is shown in Figure 6. ing. Pulses with a peak value of +45 kV, a width of 200 nanoseconds, and a repetition rate of 60 Hz. Various values of DC bias voltage were superimposed on the bias voltage. S　O211000pp The test gas containing H,02,5% by volume was at a temperature of 22°C and a flow rate of 4.1 # /minute. The length of the exposed part of the discharge wire electrode was 5 cm. Ta. Strif corona always occurs on the exposed metal surface of the wire electrode. from the surface, and the streamer extends not far from this point of origin in the axial direction. The length of the area that can process the mixed gas is determined by the discharge wire electrode. It can be considered to be the same as length. Therefore, the processing time for mixed gas is When the amount is 4.1 A/min, it becomes 5.7 seconds. Removal rate of S02 is DC via The higher the voltage, the better. The pulse voltage is +45kV, and the DC bias voltage is When the pressure was +15 kV, the SO2 removal rate was 99.8%. stream mako After using the Rona generator, it is observed that the discharge wire electrode is covered with white powder. It was done. This white powder and mist were observed adhering to the recovery electrode.

Above step) 802 removal rate when using IJ-McCorona generator at higher temperature are summarized in Table 1. The peak voltage vP is +45kV, and the DC bias voltage V A pulse voltage of +10 kV dc was used. Processing time of mixed gas is 5.7 at 22℃ seconds, 4.8 seconds at 80°C, and 4.4 seconds at 110°C. The removal rate of S02 depends on the temperature. When it goes up, it goes down. This is probably due to the shorter processing time. Also, The increase in the rate of reverse reactions during the S02 removal process also contributes to the decrease in the S02 removal rate. This can be considered as a cause.

In order to improve the S02 removal rate and promote the formation of solid products, additives are required. Additives (eg NHs) may be added to the gas stream. Streamer corona outbreak mentioned above The energy required for the device is less than when using a high-energy electron beam. Sai. Regarding this, Mizuno et al., Conf, Rec, of IEEE/J Published in AS Annual Meeting, Chicago, IL, page 1015, October 1984. ing.

The following experiment was conducted to investigate the effect of solid fine particles on the S○2 removal rate.

Regarding the case where fly ash is included in the gas flow and the case where it is not included The S02 removal rate of the Makorona generator was measured. Fly ash has an average diameter of 5 to 10 μm. The density was set to 4 g/m'. S　O211000pp and H2O2 The same operation as in Example 1 was carried out for a gas flow at room temperature (22 °C) containing 5% by volume of Ta.

- To compare the S02 removal rate with and without fly ash. Therefore, the processing time of the mixed gas was shortened to 3.2 seconds. Direct current with peak value +45kV A pulsed voltage with a bias voltage of +15 kV was used. If fly ash is present, S02 removal rate improved from 55% (passage rate 45%) to 86% (passage rate 14%) . The presence of fly ash in the gas stream may cause the streamer corona generator to be recycled after use. This fly ash was observed adhering to the expropriation electrodes (34, 36, 38).

Example 3 Using a narrow high voltage pulse superimposed with a DC bias high voltage Macrona discharge was generated to remove high resistivity fly ash from the gas stream. gas flow Streamer roller with wire cylinder type electrode configuration when fly ash is present inside The particle removal rate (ηP) of the Na generator 30 was measured using the following procedure.

A case in which only DC voltage is applied, which is the same as the conventional ESP, and a case in which a narrow pulse width is applied. For the case where the voltage is superimposed on the DC bias voltage (see Figure 5), Gas conversion and recovery operations were performed using the streamer corona generator of Example 1. Ta. Cover the recovery electrode 34, 36, 38 with a 1 mm thick filter paper with high resistivity. It should be close to the state where fly ash with high resistivity is attached, and if fly ash is present, The recovery rate was measured when

Recovery rate for each particle size of the above streamer corona generator using an optical particle counter was also measured. The radius of the particles emitted from this streamer corona generator The charge ratio was also measured.

The exposed length of the discharge wire electrode 32 was 10 cm. mixed gas Processing time was 3.9 seconds. Dry dust containing fly ash with an initial concentration of 4 g/m' Air at 22℃ is 12.0! ! /min. This fly ash is collected using a fluidized bed. and added. The average diameter of this fly ash was 5 to 10 μm. Under the above conditions The resistivity of this fly ash was large (10” ohm cm).Final density of fly ash (S) Measured at the outlet of the IJ-McCorona generator. The fly ash removal rate depends on the voltage It was determined based on the ratio of the density of fly ash with and without application. follow Therefore, mechanically collected fly ash is not included in determining the fly ash removal rate.

Voltage-current characteristics of streamer corona generator 30 with wire cylinder type electrode configuration A graph of is shown in FIG. Same as conventional ESP that applies DC voltage. If a DC voltage is applied to the discharge wire electrode 32 so that the It was observed that the current increases due to the amount of electricity generated, and a characteristic hysteresis appears. Ta. As the DC voltage value increases, corona begins to occur at +20kV, and then A back coronavirus outbreak immediately occurred. The current increased rapidly. Then the voltage drops The current became zero when the voltage was +15kV. In FIG. 7, the pulse (V, = 45 kV) and DC bias voltage are superimposed, V-'! A graph showing the characteristics is also drawn. (when performing gas conversion and recovery processing). DC bias voltage V dc is + No rapid increase in current was observed when the voltage was lower than 15 kV. this is, This means that no back-corona has occurred. DC bias voltage Vdc is +1 When the voltage exceeds 5kV, the current increases rapidly due to back corona and hysteria occurs. Sith has been observed.

The particle removal rate was determined using a pulsed voltage with a DC bias of +15kV. Observed. Therefore, a state in which no back corona occurs is achieved between the two pulses. ing. The removal rate is determined by the weight with and without voltage applied (when the filter is removed at the outlet). (see Table 2). DC electricity Removal rates using only pressure (+25 kV) were also measured. Pulse and DC vias The removal rate was 50% (passage rate 50%) when the strips were overlapped. In contrast to this When only DC voltage was used, the removal rate was 7% (passage rate 93%). Removal The rate does not include mechanically collected fly ash, so if only DC voltage is used, It is reasonable that the removal rate would be lower (due to the back corona).

■,: Peak value of pulse voltage Vdc: DC bias voltage J: Current density Using an optical particle counter, we also measured the passage rate of each fly ash particle size under the same conditions. (See Table 3). In case of small particle size (diameter less than 5 μm), The error rate was less than 10%. On the other hand, the passage rate of larger fly ash depends on the particle size. It also increased. The passage rate increases as the particle size increases, which means that the fly ash fineness increases. This means that the particles return to the gas stream and form clumps of particles together. The particle size is The passage rate of fly ash of 3 to 5 μm is determined by applying a pulse voltage that is a combination of a DC bias voltage. When using only DC voltage, it was about 2.

When using a pulsed voltage that is superimposed on a DC bias voltage, the pulse During this time, the IJ-ma hits the particulate layer, so the particulates return to the gas flow. . When only current and voltage are used, particles are returned to the gas flow due to back corona. Ru.

Furthermore, the value of the ratio of charge to particle size (q/a) of fly ash fine particles was calculated using the method of Mizuno et al. Measured according to [Conf, Rec, of IEEE/JAS Annual Meeting, Sanfra Cisco, California, October 1982, page 1111]. for measurement A streamer corona generator is installed from the sambling point 2 mm above the probe electrode 34. A sampling tube was inserted during the test. 50 fly ash fine particles (average diameter approximately 1 μm) The distribution of the ratio q/a of the sample consisting of is shown in FIG. DC bias voltage When using a pulsed voltage with a superposition of charged only to either negative or negative. In contrast, only DC voltage When used, fly ash fine particles are charged both positively and negatively and are electrically neutral. Many particles were also observed. The value of the ratio q/a of larger fly ash particles is It is also small when pressure is used. This indicates that the fly ash particles have returned to the gas stream. are doing.

As can be seen from the three examples above, in a device with a wire cylinder type electrode arrangement. Generating a streamer corona discharge removes SO2 and/or fly ash from the gas stream. Particles can be effectively removed. Also, when generating streamer corona discharge, If ash particles are present, they will act synergistically to remove S02. I understand that. The S02 removal performance of the device with wire cylinder type electrode arrangement is The SO2 removal performance is considerably superior to that of a device equipped with a rod electrode or a flat electrode.

This will be explained below while comparing the two. Wire cylinder type electrode arrangement Processing time of the device: 5.7 seconds, applied voltage VP = +45k V, Vde = +15k When used under the condition of V, 99.8% of S02 is removed as shown in FIG.

In devices with a bar-one-plane electrode arrangement and a point-one-plane electrode arrangement, the applied voltage is V .

= +45kVSVdc - +20kV processing time became slightly longer (6.7 seconds ), the SO2 removal rate is maximum at 85% and 94%, respectively [Mizuno et al. References]. When removing SO□, the removal rate changes exponentially, so the removal rate From 90% to 99% and from 0% to 90% or 99%? It is the same to improve from 99.9%. Therefore, wire cylinder type electric The removal rate of 99.8% due to discharge using a device with a pole arrangement is the same as that of a rod-one-plane type electrode. This value is considerably better than the removal rate of 94% obtained by discharge using a device with a similar configuration. Ru. Furthermore, in a device with a wire cylinder type electrode arrangement, the electric power used when removing SO2 is The pressure may be small and the processing time may be short.

Using short pulse voltage pulses generates extremely large electric fields without sparks. can be done. This results in the formation of stronger and more uniform streamers than before. Ru. The streamer will reach farther if the voltage polarity is positive instead of negative. Therefore, a wider area can be covered. Pulsed streamer corona discharge is extremely High energy efficiency. This is because most of the current is due to the movement of electrons. The ion current while the pulse is applied and the ion rotation between the two pulses are This is because the energy loss caused by the loss is small. Superimpose DC bias voltage By using a pulsed voltage, the peak voltage can be increased, so the streamer Become stronger. Therefore, the energy due to the ions moving due to the DC bias voltage Decide the DC voltage to maximize the overall efficiency, taking into account the gyros. honest honesty Using narrow positive pulse high voltages superimposed on the gas flow bias high voltage It is possible to remove the SO2 inside and collect floating fly ash fine particles. straight The current bias voltage should be set to a value smaller than the voltage at which DC corona begins to occur. To prevent back corona from occurring even when the resistivity of particles is extremely high.

According to the present invention, in one device, mainly utilizing the IJ-Macron, Simultaneously removes SO□ and/or No.2 and high-resistivity fine particles from the gas stream. A method of removing is provided. This method removes only S02 and NOx from the mixed gas. Superior to known methods of removal. The key to the success of this invention is that the streamer Wire cylinder type electrode arrangement and wire plate type electrode in corona generator By using this arrangement, it is possible to obtain a The unexpected result of a removal rate of S02 was found, and the DC bias A trimmer corona is used to simultaneously circulate SO□, NoX, and suspended particles with high resistivity. The key point is that unexpectedly excellent results can be obtained by combining these two methods.

The method of the invention removes more than 90% of S02 and NOx from a gas stream. be able to. Moreover, if there are suspended particles in this gas flow, the removal rate will be low. further improve. Furthermore, the recovery rate of suspended particles using the above device is is covered with a high-resistance layer, the recovery rate using a sedimentation device that applies a DC voltage will be lower. The size will also be much larger.

The method and apparatus of the present invention removes the above impurities from a mixture with any other gaseous components. It can be used to remove.

In particular, the method and apparatus eliminate the aforementioned impurities from air, flue gases, exhaust gases, etc. suitable for removing.

[Wire cylinder type electrode arrangement j means that the discharge wire electrode and the cylinder type electrode are co-located. Table meaning any known arrangement spaced so as to generate rona. It is current. For example, a wire electrode is placed coaxially within the cylinder electrode. Also," "Wire plate type electrode arrangement" means that two or more discharge wire electrodes are arranged in a row. An expression meaning any known arrangement arranged between two mutually parallel plate electrodes. It is. Regarding the above expression, see chapter 3 of Oglesby et al.'s ``Electrostatic Sedimentation Method,'' Dyeing Engineering and Technology Series, Young et al., Marcel Rudetzker, New York. See Ku and Basel (1978), pages 32 and 36.

To carry out the method of the present invention, one or more sets of wire cylinder type electrodes are used. (The number used depends on the volume of the area through which the gas flows). In this case, depending on the applied voltage, The diameter of the cylinder electrode is approximately 1 cm to 1 m, and the diameter of the wire electrode is approximately 0.1 mm to 1 m. Preferably, it is about 5 cm.

One or more sets of wire plate type electrodes are used to carry out the method of the invention. (the number used depends on the volume of the area through which the gas flows). In this case, apply Depending on the voltage applied, the spacing between the plates is from about 1 kV to about 1 m, and the spacing between the wires is about 1 m. Make the fence ~30cm. Also, the diameter of the wire electrode should be about 0.1 m to about 5 cm. . The device of the present invention applies a pulse-like positive or negative voltage that rises quickly and has a narrow width. Make it work by doing this.

A bias voltage may be superimposed on this pulse voltage. In this case, the pulse width and The pulse voltage is approximately 1kV to approximately 500kV depending on the value of the ear voltage, and the pulse repetition frequency is approximately 1kV to approximately 500kV. The temperature is approximately IH2 to 10kHz. The rise time of the above narrow pulse voltage is Must be as short as possible. Its value is about 100V/nanosecond to about 10 0 kV/nanosecond is preferred.

The width of the narrow pulse voltage mentioned above is necessary for the formation and propagation of the IJ-ma. Although long enough, the streamer creates a spark that creates a conductive path between the electrodes. be shorter than the time needed to That is, its value is from about 10 nanoseconds to about 10 microseconds depending on the interval between and the applied voltage.

The method of the present invention can be used to convert S02 and/or NOX without recovering particulates. If the bias voltage is used only for to a value equal to or greater than that needed to collect the ions in the gap. Ru. That is, its value depends on the spacing between the electrodes, the pulse repetition frequency, and the pulse width. From about 100V to about 10kV depending on the situation.

When using the method of the present invention to recover fine particles and/or S O2 and NOX, , the magnitude of the DC bias voltage is smaller than the value at which back corona occurs, and this Particles are charged and made large enough to be removed from between the gaps between the electrodes. .

In other words, its value depends on the resistivity of this fine particle, the voltage at which DC corona begins to occur, and its value. The voltage is about 1 kV to 200 kV depending on the spacing between the electrodes.

Those skilled in the art will understand that the term "wire" herein refers to a wire that generates a corona discharge. It will be understood that any wire known in the art for use in inside the wire has various cross-sectional areas such as circles, ellipses, squares, rectangles, narrow strips, and star shapes. Includes wires.

To Fl, 2゜ Fl(9,3 FIG 6゜ international search report ANNEX Toτ-INTERNATIONAL 5EARCHREPORT OrQ

Claims (49)

[Claims] 1. Combination of sulfur dioxide and/or nitrogen oxides with at least one other gas In order to convert into a separable form in a gas mixture, Within the streamer corona discharge area defined by spaced electrodes The above-mentioned mixed gas is passed through the streamer, and a sufficiently large A pulsed stream is generated by periodically dissipating the electrical energy of the pulsed voltage. Sulfur dioxide and/or nitrogen oxides are acidified by continuously generating Macrona discharge. in a method of converting into aerosol mist and/or aerosol particles, The above streamer corona discharge can be carried out using wire cylinder type electrode arrangement or wire plate arrangement. It is characterized by an improvement in that it is generated in the area between the electrodes of a flat-type electrode arrangement. How to do it. 2. characterized by comprising an operation of separating the aerosol particles from the mixed gas. The method according to claim 1. 3. Claim 1, characterized in that said at least one other gas is air. The method described in Section 1. 4. Claim 1, wherein the mixed gas is a flue gas. Method. 5. Claims characterized in that the above-mentioned mixed gas or exhaust gas from an industrial process The method described in paragraph 1. 6. Claims characterized in that the mixed gas is exhaust gas from an internal combustion engine. The method described in paragraph 1. 7. In the above wire cylinder type electrode arrangement, the discharge wire electrode is inside the cylinder electrode. The method according to claim 1, which includes a coaxially installed configuration. Law. 8. The wire electrode has a diameter of about 0.1 mm to about 1 cm, and the cylinder electrode has a diameter of about 0.1 mm to about 1 cm. The method according to claim 7, characterized in that the diameter is about 1 cm to about 1 m. Law. 9. Multiple wire electrodes are arranged in a line in the above wire plate type electrode arrangement. A claim characterized in that it includes a configuration installed between mutually parallel plate electrodes. The method described in item 1 of the scope. 10. The diameter of the wire electrode for discharge is about 0.1 mm to 1 cm, and the wire electrode The distance between the electrodes is about 1 mm to about 30 cm, and the distance between the plate electrodes is about 1 cm. 10. A method according to claim 9, characterized in that the distance between m and about 1 m. 11. The above energy has a pulse-like period of about 10Hz to about 100kHz. A method according to claim 1, characterized in that: 12. The peak voltage of the pulse is about 1 kV to about 500 kV. The method according to claim 1. 13. The pulse is narrow, with a width of about 1 nanosecond to about 10 microseconds, and It is characterized by a rise time of about 100kV/nanoseconds to about 100V/nanoseconds. The method according to claim 1. 14. Claims characterized in that said narrow pulses are all of the same polarity. The method described in paragraph 1. 15. 15. A method according to claim 14, characterized in that said polarity is positive. 16. 15. A method according to claim 14, characterized in that said polarity is negative. 17. A bias voltage is applied to the streamer corona discharge region, and this bias voltage is pressure is less than that required for back corona or spark to occur and the gas is sufficient to remove ions from this streamer corona discharge region. A method according to claim 1, characterized in that: 18. Reverse the polarity of the above bias voltage in synchronization with the disappearance of one pulse. 18. A method according to claim 17, characterized in that: 19. Claim characterized in that the bias voltage is about 100V to about 10kV. The method according to item 17. 20. The bias voltage is a DC voltage with the same polarity as the pulse. 18. The method according to claim 17. 21. The bias voltage is a DC voltage with a polarity different from that of the pulse. 18. The method according to claim 17. 22. Claim 17, wherein the bias voltage is an alternating current voltage. The method described in. 23. A claim characterized in that at least one additive is added to the mixed gas. The method described in item 1 of the scope. 24. The additive is ammonia (NH3) or water vapor. A method according to claim 21. 25. Claim 21, wherein the additive is a particulate matter. Method described. 26. The particulate matter is quicklime (CaO) or limestone (CaCO3) 26. A method according to claim 25, characterized in that: 27. sulfur dioxide and/or nitrogen oxides and/or particulate matter, A method of converting into a separable form in a gas mixture with at least one gas. Then, the mixed gas and/or the particulate matter are transferred to a wire cylinder type electrode. For discharging electrodes spaced apart from each other, including wire plate or wire plate electrode arrangements. Pass through the streamer corona discharge region defined by the electrode and the collection electrode, ( 1) Electrical energy of a pulse voltage of sufficient magnitude within this streamer corona discharge region Pulsed streamer corona discharge is generated continuously by periodically dissipating the energy. (2) applying a bias high voltage to this streamer corona discharge region; sulfur dioxide and/or nitrogen oxides in an acidic mist and/or aerosol. converting it into particles and charging the aerosol particles and/or the particulate matter. A method characterized in that the method is characterized in that the recovery electrode is directed toward the recovery electrode, and the recovery electrode is used to recover . 28. High resistivity is placed on or near the inner surface of the cylindrical recovery electrode. 28. The method of claim 27, comprising a layer. 29. Claims characterized in that the at least one other gas is air. The method according to paragraph 27. 30. Claim 27, characterized in that the mixed gas is a flue gas. How to put it on. 31. Claim 27, wherein the particulate matter is fly ash. Method described. 32. In the above wire cylinder type electrode arrangement, the discharge wire electrode is inside the cylinder electrode. Claim 27 includes a configuration coaxially installed in the the method of. 33. The wire electrode has a diameter of about 0.1 mm to about 1 cm, and the cylinder electrode has a diameter of about 0.1 mm to about 1 cm. Claim 32, wherein the poles have a diameter of about 1 cm to about 1 m. the method of. 34. In the above wire plate type electrode arrangement, multiple wire electrodes are arranged in a line. The claim includes a configuration in which the plate electrodes are placed between mutually parallel plate electrodes. Scope of Claim 27. The method according to item 27. 35. The diameter of the wire electrode for discharge is about 0.1 mm to 1 cm, and the wire electrode The spacing between the electrodes is about 1 mm to about 30 cm, and the spacing between the plate electrodes is about 1 c. 35. The method of claim 34, wherein the distance is between about 1 m and about 1 m. 36. The above energy must have a pulse-like period of approximately 10Hz to approximately 100kHz. 28. A method according to claim 27, characterized in that: 37. The peak voltage of the pulse is about 1 kV to about 500 kV. 28. The method according to claim 27. 38. The pulse is narrow, with a width of about 1 nanosecond to about 10 microseconds, and It is characterized by a rise time of about 100kV/nanoseconds to about 100V/nanoseconds. 28. The method according to claim 27. 39. Claims characterized in that said narrow pulses are all of the same polarity. The method according to paragraph 27. 40. 40. A method according to claim 39, characterized in that said polarity is positive. 41. A bias voltage is applied to the streamer corona discharge region, and this bias voltage is The pressure is less than that required to produce a back corona or spark, and fine particles be sufficient to remove particulate matter from this streamer corona discharge region; 28. A method according to claim 27, characterized in that: 42. A claim characterized in that the bias high voltage is about 1 kV to about 100 kV. The method according to item 39. 43. characterized in that said bias high voltage has the same polarity as said narrow pulse; 43. The method of claim 42. 44. Remove the aerosol and/or particulate matter from the gas mixture 28. A method according to claim 27, characterized in that the method is characterized in that it is agglomerated without being agglomerated. 45. A claim characterized in that at least one additive is added to the mixed gas. The method according to item 27. 46. The additive is ammonia (NH3) or water vapor. 46. The method of claim 45. 47. Claim 45, wherein the additive is a particulate matter. Method described. 48. The particulate matter is quicklime (CaO) or limestone (CaCO3) 48. A method according to claim 47, characterized in that: 49. Reverse the polarity of the above bias voltage in synchronization with the disappearance of one pulse. 28. A method according to claim 27, characterized in that: